1. Field of the Invention
The present invention relates generally to an improved design for a prime mover of the type used in supplying power for a variety of roles in industrial applications, including oil and gas well operations, such as the prime mover which is used to operate a pump jack at a well site, or which is used to operate an injection well.
2. Description of the Prior Art
Oil and gas well production operations require a variety of different power sources for such things as running gas compressors, running of injection wells, or operating the pump jack present at the well site. Pump jacks are widely used at the present time at the surface of an oil well to reciprocate lift pumps, located downhole in the well, for lifting subsurface fluids to the surface of the well. A lift pump usually includes a tubular barrel and a cooperating plunger assembly which reciprocates within the barrel. The plunger assembly is attached to a rod string which extends to the surface of the well and by which the plunger assembly may be reciprocated by the pump jack.
A typical pump jack may comprise a supporting post and a walking beam, having a head end and a tail end, pivotally connected to the post to allow for rocking of the beam about a horizontal pivot axis between one position, in which the head end is up and the tail end is down, and another position in which the head end is down and the tail end is up. It is the head end which is normally connected to the upper end of a vertical pump rod string, at the lower end of which is the lift pump. The walking beam is typically connected to one end of an arm, the opposite end of which connected to a drive assembly. The drive assembly provides the motive force to rock the beam about its horizontal pivot axis to reciprocate and produce a predetermined number and rate of up and down strokes of the pump rod string. The drive assembly typically includes a rotating power device which will be referred to in the discussion which follows as a “prime mover.” The prime mover is typically either an electric motor or a gas combustion engine and is typically connected by sheaves and belts to a power transmission assembly, e.g. a gear box, whereby rotation of the prime mover's output shaft is translated to a longitudinal force on the arm for rocking of the beam. Pump jacks of this type are well known in the oil and gas industry, having been used for many years. Examples of such pump jacks may be seen in the following U.S. Pat. Nos. 4,238,966; 4,454,778; 4,492,126; 4,723,452 and 4,743,172, among others.
The present invention deals with the prime mover component which is used for such tasks as operating the pump jack in the manner previously described. Despite advances which have been made over the years in the design of prime movers of the type under consideration, a need continues to exist for further improvements.
It would be particularly advantageous to provide such a prime mover which could be run on common oil field fuels, including natural gas, propane, or methane, and which offered an improved design for maximizing production and increasing labor efficiency of the device when used in oil field and industrial pumping operations.
Additionally, one particular area in need of improvement in many of the existing prime mover designs is the oil supply system of the unit. It would be particularly advantageous to provide a prime mover with one or more oil reservoirs for storing and supplying oil to the engine of the prime mover. Increasing the volume of oil available would extend the time period between required oil changes. It would also keep the engine cooler during normal operation, thereby extending the engine life.
It would also be advantageous to provide the aforesaid oil reservoirs for the engine of the prime mover with the reservoirs being integrated into the design of the housing framework of the prime mover itself, rather than being externally located. This would result in a simplified design which would provide economy of manufacture.